"The Dominican Republic is the only place on Earth where the amber fauna [fossilized animals in amber] are almost identical to the recent fauna," he explained. "That tells us that [Hispaniola] was tropical at the time it was formed."

The island's amber fossil record may also help turn up previously unknown species still living today, Penney said.

"The fauna on the island is quite poorly known. Not all the species are described," he said. Descendants of the newly discovered fossil spider may well have survived on Hispaniola, he added.

The paleontologist used blood droplets visible in the amber fossil, which is 4 centimeters long and 2 centimeters wide (1.6 inches long and 0.8 inch wide), to determine how the spider met its end.

From the flow of the blood droplets, Penney says, the spider must have been struck head-on by tree resin as it flowed down a tree trunk.

When the resin engulfed the spider, blood oozed from the arachnid's legs, which broke at predetermined weak spots. Leg loss is a predator-escape mechanism that is not unique to spiders.

"[It's] a bit like when you catch a lizard's tail and it breaks off," Penney said. "The same happens with spider legs in some families."

Replacement Limbs

But can DNA be extracted from amber-preserved blood? And could it be used to sequence the DNA of long-extinct animals?

Experts are highly skeptical on both counts.

Along with other researchers, a team at the Natural History Museum in London recently tried to replicate experiments of scientists who claimed to have extracted insect DNA from amber fossils. These attempts all failed.

As a result, said the museum's ancient DNA expert Jeremy Austin, "Most scientists now agree that DNA doesn't survive in fossilized insects in amber."

And even if insect DNA was recoverable from amber fossils, the team says the chances of getting dinosaur DNA from a Jurassic-era mosquito are "virtually nonexistent."